9,942 research outputs found
Why we love music : a case study of high school principals.
The purpose of this qualitative study was to explore the viewpoints and value of music in the public schools from the perspective of high school principals. Principals from five high schools in an urban school district in a southern metropolitan area were interviewed. All schools that were a part of this study varied geographically and socioeconomically. Each school had a curricular program for band, choir, and orchestra and a highly-qualified teacher directing the programs. Interview questions ranged from their own participation in band, choir, or orchestra when they were in any level of school, what roles they see music as having in their school, and why they choose to keep music in their schools when, elsewhere, programs are being cut to save money. The administrators had a high regard for music in their own lives, as well as in the lives of their students. Some of these principals even viewed music as a direct supporter of the 21st century skills that are so widely emphasized and promoted. Music is actively supported at all levels of this school district, from the Board of Education to the individual students
The Panchromatic Hubble Andromeda Treasury. VI. The reliability of far-ultraviolet flux as a star formation tracer on sub-kpc scales
We have used optical observations of resolved stars from the Panchromatic
Hubble Andromeda Treasury (PHAT) to measure the recent (< 500 Myr) star
formation histories (SFHs) of 33 FUV-bright regions in M31. The region areas
ranged from ~ to pc, which allowed us to test the reliability
of FUV flux as a tracer of recent star formation on sub-kpc scales. The star
formation rates (SFRs) derived from the extinction-corrected observed FUV
fluxes were, on average, consistent with the 100-Myr mean SFRs of the SFHs to
within the 1 scatter. Overall, the scatter was larger than the
uncertainties in the SFRs and particularly evident among the smallest regions.
The scatter was consistent with an even combination of discrete sampling of the
initial mass function and high variability in the SFHs. This result
demonstrates the importance of satisfying both the full-IMF and the
constant-SFR assumptions for obtaining precise SFR estimates from FUV flux.
Assuming a robust FUV extinction correction, we estimate that a factor of 2.5
uncertainty can be expected in FUV-based SFRs for regions smaller than
pc, or a few hundred pc. We also examined ages and masses derived from UV
flux under the common assumption that the regions are simple stellar
populations (SSPs). The SFHs showed that most of the regions are not SSPs, and
the age and mass estimates were correspondingly discrepant from the SFHs. For
those regions with SSP-like SFHs, we found mean discrepancies of 10 Myr in age
and a factor of 3 to 4 in mass. It was not possible to distinguish the SSP-like
regions from the others based on integrated FUV flux.Comment: Accepted for publication in The Astrophysical Journa
Virtual Forestry Generation: Evaluating Models for Tree Placement in Games
A handful of approaches have been previously proposed to generate procedurally virtual forestry for virtual worlds and computer games, including plant growth models and point distribution methods. However, there has been no evaluation to date which assesses how effective these algorithms are at modelling real-world phenomena. In this paper, we tackle this issue by evaluating three algorithms used in the generation of virtual forestsâa randomly uniform point distribution method (control), a plant competition model, and an iterative random point distribution technique. Our results show that a plant competition model generated more believable content when viewed from an aerial perspective. Interestingly, however, we also found that a randomly uniform point distribution method produced forestry which was rated higher in playability and photorealism, when viewed from a first-person perspective. We conclude that the objective of the game designer is important to consider when selecting an algorithm to generate forestry, as the algorithms produce forestry that is perceived differently
The Singular Hydrodynamic Interactions Between Two Spheres In Stokes Flow
We study exact solutions for the slow viscous flow of an infinite liquid
caused by two rigid spheres approaching each either along or parallel to their
line of centres, valid at all separations. This goes beyond the applicable
range of existing solutions for singular hydrodynamic interactions (HIs) which,
for practical applications, are limited to the near-contact or far field region
of the flow. For the normal component of the HI, by use of a bipolar coordinate
system, we derive the stream function for the flow as and a formula
for the singular (squeeze) force between the spheres as an infinite series. We
also obtain the asymptotic behaviour of the forces as the nondimensional
separation between the spheres goes to zero and infinity, rigorously confirming
and improving upon known results relevant to a widely accepted lubrication
theory. Additionally, we recover the force on a sphere moving perpendicularly
to a plane as a special case. For the tangential component, again by using a
bipolar coordinate system, we obtain the corresponding infinite series
expression of the (shear) singular force between the spheres. All results hold
for retreating spheres, consistent with the reversibility of Stokes flow. We
demonstrate substantial differences in numerical simulations of colloidal
fluids when using the present theory compared with existing multipole methods.
Furthermore, we show that the present theory preserves positive definiteness of
the resistance matrix in a number of situations in which
positivity is destroyed for multipole/perturbative methods.Comment: 28 pages, 12 Figure
Mapping Low-Density Intergalactic Gas: a Third Helium Lyman-alpha Forest
We present a new HST/STIS spectrum of the z=3.18 quasar PKS 1935-692 and
summarize the spectral features shortwards of 304A in the rest frame likely to
be caused by foreground HeII Lyman-alpha absorption. In accord with previous
results on two other quasars at similar redshifts, we demonstrate a correlation
with the HI Lyman-alpha forest absorption, and show that much of the helium
absorption is caused by a comparable quantity of more diffuse gas with
Omega~0.01, that is not detected in HI. The helium ionization zone around the
quasar is detected as well as a void seen in both HI and HeII. The properties
of the absorption are in broad agreement with those of the other quasars and
with models of the protogalactic gas distribution and ionization at this
redshift.Comment: 17 pages including 5 figures. As accepted for publication in The
Astronomical Journal (minor revisions
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